How to Make Your Own Seed-Starter Mix

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If you live in an area that has cold and snowy winters, the best way to feel like winter is shorter than it really is or that spring is here before it really is is to start seeds indoors. You’ll observe seedlings emerge 4 to 6-ish weeks before you can place seeds in the ground.Optimal seed-starter mix will allow for the following:

Probably the two most common mediums used for “soil”, moisture retention, and the “glue” that keeps everything together are coir and sphagnum peat moss. (Compost also has these characteristics.)

Coir is the by-product of coconut processing. Other names for coir are coco/coir peat, fiber, pith, or dust. You’ve probably picked up on the fact that “coco” is short for coconut NOT cocoa.

Both coir and sphagnum peat moss have amazing water-holding capacity. Keeping your seeds and seedlings from drying out can be the difference between success and failure. And, although they can hold a lot of moisture, they’re still fluffy and airy.

I’ll probably have a post later in the year on the similarities and differences between coir and sphagnum peat moss.

Perlite and Vermiculite

According to Iowa State University Extension, “perlite is a natural occuring volcanic glass … .” (1) It’s white, somewhat round, and its appearance has been compared to little pieces of styrofoam.

Vermiculite is a mineral. (2) It’s brown and grey, with a sheen, and more boxy or rectangular (unless ground finely).

Both perlite and vermiculite are inorganic. If you’re a newbie gardener you might think that’s a bad thing; after all, organic has been the buzz word for quite some time now.

Because they’re inorganic they won’t decompose. Decomposition is a good thing, but it’s also good to have some of your soil structure that will remain intact.

Perlite has microscopic air pockets that both provide oxygen pockets for microbes and plant roots as well as hold water for plants’ future use. (1) Vermiculite will expand somewhat when it gets wet and is said to contain some minerals.

You shouldn’t have any trouble finding perlite at your local home and garden store. Vermiculite, on the other hand, might not be as easy to find. One of my home and garden stores, while they will carry it soon, did not have any at this time so I ordered Plantation Products Inc G208 Vermiculite 8 Qt (affiliate link) from Amazon.Vermicompost or Compost

Vermicompost will promote the overall health of your plants. It provides both nutrients AND the beneficial microbes that make these nutrients plant-ready.

Even though my seedlings will only be in their trays for a few weeks, it’s still good to give them a healthy start. If you don’t have vermicompost available you can purchase it online, or you can simply use compost.

This is my seed-starter mix WITHOUT the vermicompost. I’ll be adding the vermicompost right before I plant my seeds in the seed-starter mix. I used 8 parts coir.

Directions:

Coir or Sphagnum Peat Moss – Pre-soak. If you choose to use coir, it will probably come in a “brick.” There should be sufficient instructions with the coir, but, basically, you’ll place it in a bag or container and add the prescribed amount of water. Within minutes and with very minimal massaging, the coir will turn from a hard brick into a fluffy mix.

Perlite – Do a little homework on this. The bags of perlite have a lot of perlite dust which is very harmful if inhaled. Also be careful not to get it in your eyes. Some recommend getting the perlite wet before working with it to keep the dust down.

Vermiculite – Not a lot to say about this one.

Vermicompost or Compost – Again, not much to say except to be sure it’s not chunky. You want fine particles.

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Great informative post!! I’ve never made my own seed starter mix, but I think I can do this! I’m going to feature you in this week’s Homeacre Hop! Please join us again soon!
Mary http://www.homegrownonthehill.blogspot.com

Perfect timing! I was just thinking I need to search for a seed started mix. Now I don’t need too ;0)
I have heard that the moss is non-renewable. I don’t know how accurate that is, but I think I will try the coir. I used that a few years ago with our worm farm and I liked it.
Now I know what I will be doing this weekend- buying seeds and supplies to make some starter mix!

I am a state certified asbestos inspector in the state of MS. I thought you might want to know, asbestos is a contaminant of vermiculite. Not all vermiculite contains asbestos, but knowing what I do I will not use it. Vermiculite is why Libby Montana is a Super Fund Site.

A little late on starting my seeds. May go ahead and order this and get started this coming week when my materials come in. Do you put the starter mix in pots or do you use another source for the starter seeds?